Magnetic excitation and hole doping effects of Haldane system

Haldane体系的磁激发和空穴掺杂效应

• 批准号: 12440105
• 负责人: AKIMITSU Jun
• 金额: $ 8.77万
• 依托单位: AOYAMA GAKUIN UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12440105/
• 关键词: Haldane; Singlet; One-dimensional; Magnetic excitation

After the quantum fluctuations in Haldane system have been observed, a lot of research has been performed both from theoretical and experimental sides. Antiferromagnetism can be induced by impurity doping in the non-magnetic gapped Haldane system. In this impurity doped Haldane system, antiferromagnetism and gapped Haldane state coexist, resulting in the magnetic new state.We tried to observe the magnetic excitations in the carrier doped Haldane system, paying attention to the carrier (hole) dependence. In order to observe the detailed physical properties with neutron scattering experiments, Nd_2BaNiO_5 was chosen for which a large-sized single crystal can be available. The Haldane gap in Nd_2BaNiO_5 has shown the similar behavior to that of pure Haldane system Y_2BaNiO_5 above T_N. The Haldane state coexists with antiferromagnetic state below T_N, which was recently recognized as a unique model of Haldane gap quantum spin chain in a staggered applied field.We clearly observed the dynamical incommensurate structure above T_N in the hole doped (Nd, Ca)_2BaNiO_5. The incommensurability δ is not proportional to the hole concentration. This corresponds to the relationship between the hole concentration and δ in the copper oxide superconductor. A new magnetic dispersionless excitation was observed with hole doping below T_N, although this excitation energy is higher than the energy currently expected. In order to observe this magnetic excitation, we try to use the ESR technique having a better energy resolution. Since we succeeded in growing a large single crystal of (Nd, Y, Ca)_2BaNiO_5 for which we can control the influence of magnetic Nd ion freely, we will perform the neutron experiment in near future..

自从观测到Halfenite系统中的量子涨落以来，人们从理论和实验两个方面进行了大量的研究。在非磁性带隙的Haldrons系统中，杂质掺杂可以引起反铁磁性。在这种杂质掺杂的半导体系统中，反铁磁性和带隙的半导体态共存，产生了磁性新态，我们试图观察载流子掺杂半导体系统中的磁激发，注意载流子（空穴）的依赖性。为了用中子散射实验观察其详细的物理性质，选择了可获得大尺寸单晶的Nd_2BaNiO_5。在T_N以上，Nd_2BaNiO_5中的Half带隙表现出与纯Half带隙Y_2BaNiO_5相似的行为。在T_N以下，Half态与反铁磁态共存，这是最近发现的在交错场作用下Half带隙量子自旋链的唯一模型，我们在空穴掺杂的（Nd，Ca）_2BaNiO_5中观察到了T_N以上的动力学无公度结构。介电常数δ与空穴浓度不成正比。这对应于铜氧化物超导体中空穴浓度与δ之间的关系。在T_N以下观察到空穴掺杂的一种新的无磁色散激发，尽管这种激发能量比目前预期的能量高。为了观察这种磁激发，我们尝试使用具有更好能量分辨率的ESR技术。由于我们成功地生长出了（Nd，Y，Ca）_2BaNiO_5大单晶，可以自由地控制磁性Nd离子的影响，我们将在不久的将来进行中子实验。

项目成果

M.Sera, H.Ichikawa, T.Yokoo, J.Akimitsu et al.: "Anomalous Temperture Dependence of the Magnetic Field Induced Antiferromagnetic Moment int the Antiferroquadrupolar Ordere State of CeB_6"Phys. Rev. Lett.. Vol.86 No.8. 1578-1581 (2001)

M.Sera、H.Ich​​ikawa、T.Yokoo、J.Akimitsu 等人：“CeB_6 反铁四极有序态中磁场感应反铁磁矩的异常温度依赖性”

E.Nishibori, M.Takata, T.Muranaka, J.Akimitsu et al.: "Bonding Nature in MgB_2"J. Phys. Soc. Jpn.. Vol.70 No.8. 2252-2254 (2001)

E.Nishibori、M.Takata、T.Muranaka、J.Akimitsu 等：“MgB_2 中的键合性质”J。

C.Sekar, T.Watanabe, Y.Zenitani, J.Akimitsu et al.: "Effect of silver addition on structure and electrical properties of the spin ladder compound La_2Cu_2O_5 single crystal"J. Crystal Growth. 233. 466-472 (2001)

C.Sekar, T.Watanabe, Y.Zenitani, J.Akimitsu等：“银添加对自旋梯化合物La_2Cu_2O_5单晶结构和电学性能的影响”J.

J.Akimitsu, H.Ichikawa, N.Eguchi, T.Miyano et al.: "Direct Observetion of Orbital Ordering in YTiO_3 By Means of the Polaized Neutron Diffraction Technique"J. Phys. Soc. Jpn.. Vol.70 No.12. 3475-3478 (2001)

J.Akimitsu、H.Ich​​ikawa、N.Eguchi、T.Miyano 等：“利用极化中子衍射技术直接观察 YTiO_3 中的轨道有序性”。

M.Sera, F.Iga, S.Kobayashi, H.Sugamoto, J.Akimitsu et al.: "Ce site substitution effects on the multipolar interactions in CeB_6"J. Phys. Soc. Jpn.. 71 Suppl.. 52-55 (2002)

M.Sera、F.Iga、S.Kobayashi、H.Sugamoto、J.Akimitsu 等：“Ce 位点取代对 CeB_6 多极相互作用的影响”J。